System of distribution.



, J. F. PETERS.

v SYSTEM OF DISTRIBUTION.

APPLICATION FILED OCT. 6, IQIS.

Patented Jan. lfl, 1919.

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fr 0e, 6 WITNESSES a 7 ATTORNEY UNITED STATES PATENT oEEIoE.

JOHN F. PETERS, 0F EDGEWOOD PARK, PENNSYLVANIA, ASSICNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

SYSTEM OF DISTRIBUTION.

Application filed October 6, 1915.

To all whom it may concern:

Be it known that 1, JOHN F. PETERS, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have in vented a-new and useful Improvement in Systems of Distribution, of which the following is a specification.

My invention relates to electrical systems of distribution for alternating currents, and it has special reference to systems from whlch it is desired to eliminate certain objectionable disturbing electrical impulses.

More particularly, my invention relates to electrical systems provided with means for automatically eliminating objectionable harmonic current and voltage impulses that tend to produce inductive disturbances in adjacent telephone, telegraphor other circuits.

It is well known that any periodic electrical impulse having a complex wave form may be resolved into a series of component impulses of sine-wave form one of which, known as the fundamental component, has

' the same frequency as the initial impulse and the others of which, known as the harmonic components, have frequencies which are multiples of the frequency of the fundamental. If certain harmonic components of selected frequencies are objectionable because they tend to produce disturbances in adjacent intelligence-transmission circuits, the disturbing harmonics should be eliminated from the power system in order to insure satisfactory operation of the intelligence-transmission circuit.

In electrical systems adapted to transmit power, it frequently happens that the waves impressed thereupon by the generating equipment comprise harmonic components which occasion disturbances in other power circuits or induce disturbances in telephone or telegraph circuits that are adjacent to and parallel the power system. If the wave forms of the power impulses are particularly complex and irregular, the upper harmonic components of the impulses may seriously interfere withthe transmission of intelligence over the affected telephone or telegraph circuits by inducing disturbing elec tromotivc forces of appreclably high values in them. It has been proposed to connect to a main circuit in which disturbing impulses obtain, an auxiliary circuit or circuits which are so tuned as to constitute short-circuiting Specification of Letters Patent.

. Patented Jan. 14, 1919.

Serial No. 54,343.

paths for the selected harmonic components to be eliminated from the system. The above-mentioned method of eliminating or filtering out the disturbing harmonic components is adequate only when the generating equipment maintains a constant speed, inasmuch as the auxiliary circuit or circuits are so adjusted as to constitute tuned circuits for selected. harmonic components having definite and constant frequencies only.

It will be appreciated that the speed of the generating equipment for a power sys tem will vary within certain limits. Since the frequencies of the disturbing harmonic components likewise vary, the disturbing components frequently induce appreciable electromotive forces in adjacent circuits when the generating equipment varies its speed within a small per cent. only.

It is essential for the satisfactory operation of intelligence-transmission circuits located in proximity to a power-transmission system that the disturbing harmonic impulses be precluded from flowing in the power system during ordinary changes in the speed of the generating equipment, and, to accomplish this end, I provide automatic means for filtering selected harmonic electrical impulses from the power system. My invention also provides automatic means for the accomplishment of the above-mentioned result that efi'ectivelyv eliminates the'selected disturbing impulses from circuit, irrespective of the speed of the alternator supplying power to the system.

To illustrate my invention, reference may be had to the following description and the accompanying drawing in which Figure 1 1s a diagrammatic view of an electrical power system embodying a form of my invent on; Fig. 2 is a diagrammatic view of a modified form of the power system shown in Fig 1; Fig. 3 is a raph illustrating the electrlcal conditions 0 taming in one of the auznhary electrical circuits employed in my lnvention, and Fig. 4 is a graph illustrating the electrical conditions which I endeavor to obtain in another auxiliary circuit employed in my invention.

Referring to Fig. 1, a source of alternating current, shownas a single-phase alternator 1 is connected to power mains 2 and 3 which are adapted to supply power to an electrical transmission system. It 1s assumed that the alternator 1 impresses Penodic impulses of complex wave form upon the mains 2 and 3, such impulses comprising harmonic components which create inductive disturbances upon an adjacent intelligence-transmission circuit shown as a telephone circuit 1. It is likewise assumed that the disturbing harmonic components have been determined and, as a consequence thereof, are to be eliminated or filtered from the power circuit in order to preclude the occurrence of inductive disturbances in the adjacent telephone circuit 4. Moreover, the alternator 1 is susceptible of slight speed variations which will effect a change in the frequency of the fundamental component of the electrical impulses generated thereby, with consequent changes in the frequencies of the harmonic components of the impulses. It is essential, therefore that the disturbing harmonic components be permanently fil tered from the power system in order that the telephone circuit 1 may be continuously operated under satisfactory conditions for the transmission of intelligence under all speed conditions of the alternator 1.

To accomplish this end, an auxiliary circuit or path 5 comprising an adjustable condensive reactance device 6, a conductor 7, relays 8 and 9, an inductive device 10 and a plurality of parallel condensers 11, is connected in shunt relationship with the mains 2 and 3. The electrical constants of the circuit 5 are so adjusted as to provide a substantially non-reactive path for the flow therethrough of the fundamental component of the impulses impressed by the alternator 1 0n the transmission system. While the aforementioned auxiliary circuit may constitute a non-reactive. path that is accurately tuned to admit the free flow therethrough of the fundamental component, I prefer that the electrical constants of this circuit be so adjusted that, at normal speed of the alternator 1, the value of the current flow therethrough shall correspond, in some degree, to that represented by the value A\in Fig. 3. In order to accomplish this, the condenser reactance elements 6 and 11 and the inductive reactance element 10 are so adjusted in value that current resonance nearly obtains in the auxiliary electrical circuit 5, with the combined values of the condensive reactance elements 6 and 11 slightly predominating over the value of the inductive reactance element 10. I prefer this circuit condition because the portion of the graph shown in Fig. 3, which represents a predominance of the condensive reactance, efiects a more rapid change in the current flowing through the associated electrical circuit when the speed of the generator 1 varies slightly. It will be understood, however, that this is a preferred form only, and that, under certain conditions, the value of the inductive reactance element 10 may predominate over that of the condensive elements 6 and 11. In both instances, the value of the current flow through the auxiliary circuit 5 will vary substantially with changes in the speed of the alternator 1 so long as accurate resonance conditions do not obtain in this circuit.

As shown in Fig. 3, a decrease in frequency of the fundamental component will effect a decreased current-flow through the auxiliary circuit 5, and an increase in the frequency of the fundamental component will effect an increased current flow through the circuit. The relays 8 and 9, being adjusted to operate on the occurrence of increased or decreased current flow through this auxiliary circuit, control the electrical circuit conditions obtaining in a second auxiliary circuit 5, which comprises an adjustable reactance element 12 and the condensive reactance elements 13, 14:, 15 and 16 that may be either cut into or out of circuit, according to the operation of the relays 8 and 9. The above-mentioned second auxiliary circuit constitutes a short-circuiting path whereby one of the disturbing harmonic components of the impulses generated by the alternator 1 may be eliminated or filtered from the power circuit. It is essential that the disturbing harmonic component be eliminated from the circuit irrespective of the speed changes of the generator 1 and, consequently, the relative values of the condensive reactance elements and the inductive reactance elements constituting the second auxiliary circuit 5 should be automatically adjusted to permanently filter out the selected disturbing harmonic component. In other Words, this second auxiliary circuit should be accurately tuned to filter out the disturbing harmonic component, irrespective of the speed of the alternator 1.

To this end, the relative values of the electrical constants of the second auxiliary circuit are adjusted automatically so that the counter-electromotive force offered to the flow of the disturbing harmonic component through the auxiliary circuit 5 may be represented by the value B shown in Fig. 4. It will be observed, therefore, that the only impedance offered to the flow of the disturbing harmonic component will be the ohmic resistance of the auxiliary circuit 5, and, under these conditions, the disturbing harmonic component will be substantially filtered from the power circuit.

Under normal operating conditions, the relay 8 may be so adjusted that the condenser elements 15 and 16 are connected in series relationship with the inductive element 12 by reason of engagement of armatures 17 and 18 with their corresponding contact members 19. When these conditions obtain, the disturbing harmonic component is completely filtered from the power circuit because the auxiliary circuit 5 is accuthe changed conditions of speed of the alternator 1.

For example, assume that the speed of the alternator 1 decreases a slight amount in value, thereby eflecting a proportional de-' crease in the frequency of the fundamental component of the electrical impulses generated by the alternator, 1. By referring to Fig. 3, it will be seen that the decrease in frequency of the fundamental component results in a decreased current flow through the windings of the relays 8 and 9. Furthermore, since the fundamental component decreases in frequency, the disturbing harmonic component suffers a corresponding decrease in frequency and, therefore, the circuit conditions obtaining in the auxiliary circuit 5 must be so modified as to constitute a resonant circuit therefor. Either one or both the armatures 17 and 18 of the relay 8 may be released, depending upon the decrease in the current flow through the first auxiliary circuit. When the armatures 17 and 18 are released, the condenser elements 15 and 16 are disconnected from circuit, the values of the condensive reactance of the condensers 15 and 16 being so calculated as to restore resonant conditions in the second auxiliary circuit at the decreased frequency. Similarly, when the speed of the alternator 1 increases in value, the condenser elements 13 and 14: of the second auxiliary circuit 5 are inserted in this circuit by reason of the increased excitation of the relay 9 which is likewise controlled by the current conditions obtaining in the first auxiliary circuit. In this manner, resonant conditions are continuously maintained in the second auxiliary circuit, automatic regulation thereof being efl'ected by means of the current flow through the auxiliary circuit 5 which, as mentioned above, constitutes a path for the flow of the fundamental component only.

In Fig. 2, I have shown a modified form of the system illustrated in'Fig. 1, the automatic regulation of the circuit conditions obtaining in the auxiliary circuit 5 for the flow of the disturbing harmonic component beingeffected by means of a constant-current regulator of a well known form of construction. In this instance, the auxiliary circuit for the flow of thefundamental component comprises an inductive reactance element 20,

a condensive reactance element 21, a movable coil 22 of a constant-current regulator 23 and a stationary coil 24. I prefer again to ad ust the electrical constants of the elements comprising this circuit so as to eifect a current fiow therethrough represented by the value A of Fig. 3, under normal conditions of speed of the alternator 1. On a variation of the current flow through the main auxiliary circuit, as a result of changes in speed of the alternator 1, the movable coil 22 will vary its position with respect to a stationary coil 24. As the coil 22 is moved, a rack 25, secured thereto, engages a pinion 26 which, in turn, actuates a conducting arm 27 that is adapted to engage taps 28-upon an inductive reactance element 29. reactance element 29, in combination with 'a plurality of condensers 30 and the conducting arm 27 comprises the auxiliary circuit 5 which is utilized to filter the disturbing harmonic component from the power system. By the variations efiected in the value of the inductive reactance 29 connected in the second auxiliary circuit, as a result of the movement of the arm 27, resonant conditions are permanently maintained in this auxiliary circuit in order to continuously provide a non-reactive path for the flow of the disturbing harmonic component. In this system, 1t will be noted that the electrical conditions obtaining in the second auxiliary circuit are automatically regulated by the current flow through the first auxiliary circuit which constitutes a path for the flow'of the fundamental component of the electrical impulses impressed on the power circuit by the alternator 1.

While I have described my invention as applied to electrical systems from whlch ii;

is desired to eliminate one disturbing comis described as being applicable to the elimination of inductive interferences with intelligence transmission circuits, it is well known that other conditions may be present in a power system which render it important to remove certain harmonic components 1n order to preclude the occurrence of high-frequency surges or disturbances, and I desire, therefore, that my invention be limited only as expressly set forth in the appended claims. I

I claim as my invention:

1. The combination with a main electrlcal circuit having electrical periodic impulses impressed thereupon that vary withm predetermined frequency limits and possess complex wave forms, of automatic filterlng means for eliminating a selected harmonic component from the main circuit, irrespec- The inductive tive of the frequency, within said limits,

of the fundamental component of said impulses. 2. The comblnatlon with a ma1 n electrical circult, and means for impressing thereupon periodic electrical impulses that vary within predetermined frequency limits and possess complex wave forms, of an auxiliary circuit connected thereto which is automatically regulated to constitute a substantially non-reactive path for a selectedharmonic component, irrespective of the frequency of the fundamental component of said electrical impulses.

3. The combination with a main electrical circuit upon which electrical impulses that vary within predetermined frequency determined range of speed variation and impressing thereupon perlodic impulses of a complex wave form, of an auxiliary circuit connected thereto which is automatically regulated to constitute a substantially non-reactive path for the flow therethrough of a selected harmonic component of said impulses, irrespective of the speed within said range of the power unit.

5. The combination with a main electrical circuit on which electrical impulses that vary within predetermined frequency limits and possess complex wave forms are impressed, of an auxiliary circuit connected thereto having its impedance automatically regulated to constitute a tuned circuit for a selected harmonic component irrespective of the frequency, within said limits, of the fundamental component of said impulses.

6. The combination with a main electrical clrcuit having periodic electrical impulses impressed thereupon that vary with in predetermined frequency limits and possess complex wave forms, of an auxiliary c1rcu1t connected thereto which constitutes a substantially unimpeded path for a selected harmonic component irrespective of the. frequency, within said limits, of the fundamental component of said impulses, another auxiliary circuit connected to the main circu t, the impedance of said first auxiliary clrcuit being automatically regulated by the electrical conditions obtaining in said second auxiliary circuit.

7 The combination with a main electrical circuit, and means for impressing thereupon periodic electrical impulses of a complex wave form, of an auxiliary circuit comprising condensive and inductive reactances, the relative values of which are automatically regulated to provide a non-reactive path for the flow therethrough of a selected harmonic component of said impulses.

8. The combination with a main electrical circuit having periodic electrical impulses of a complex wave form impressed thereupon, of an auxiliary circuit connected thereto which possesses electrical characteristics that render said circuit conducive to the flow of those components having substantially the frequency of the fundamental, and another auxiliary circuit which is automatically tuned by the electrical conditions obtaining in said first auxiliary circuit to constitute a substantially non-reactive path for the flow of a selected harmonic component of said impulses.

9. The combination with a mainelectrical circuit havin periodic electrical impulses of a comp ex wave form impressed thereupon, of an auxiliarycircuit connected thereto which is conducive to the flow of those components having substantially the frequency of the fundamental, a second auxiliary circuit, andmeans controlled by the current flow in said first auxiliary circuit for automatically controlling the value of the impedance offered to the flow of a selected harmonic component through said second auxiliary circuit.

10. The combination with a main electrical circuit and means for impressing thereupon periodic electrical impulses of a complex wave form, of an auxiliary electrical circuit comprising condensive and inductive reactance elements, the values of which are so related as to render saidcircuit conducive to the flow of those components having substantially the frequency of the fundamental of said impulses, and a second auxiliary electrical circuit comprising condensive and inductive reactance elements the relative values of which are automatically regulated by the current flow in said first auxiliary electrical circuit to constitute a tuned path for the flow of a selected harmonic component only.

In testimony whereof, I have hereunto subscribed my name this 28th day of Sept, 1915.

JOHN F. PETERS. 

